Field of the Invention
The present invention relates to a driving member for use with a linear driving device that is employed in the camera or digital camera usually mounted on an electronic device such as the mobile phone and the like. The present invention also relates to a linear driving device, a camera device and an electronic device, each of which uses the driving member of the present invention.
Description of Relevant Art
In the conventional relevant art, the small-size camera device or the like employs the linear driving device (the lens driving device) that is designed for use in driving the lens mounted on the camera device. There are various types of the driving member that have been used with the linear driving device (the lens driving device).
As one example of the driving member, there has been a zooming or focusing type of the driving member that drives the lens support having the lens mounted thereon to be moved in the linear manner by vibrating the driving shaft in the axial direction thereof.
In this conventional type of driving member, structurally and constructionally, its driving shaft is usually coupled with a vibration producing source and the lens support is frictionally coupled with the driving shaft. The vibration producing source may produce vibrations that are supplied to the driving shaft to cause the driving shaft to reciprocate in the axial direction thereof and with different speeds depending on whether the driving shaft is moved forwardly or backwardly. In this way, the driving shaft and the lens support will be placed under the different friction conditions while the driving shaft is reciprocating under the supplied vibrations. Then, this will cause the lens support to move.
For example, Patent Document 1 discloses the structure of the driving member 100 in which the driving shaft 108 is coupled with a deformable thin plate 106 as shown in FIG. 6. The deformable thin plate 106 includes a piezoelectric base plate 102 and an elastic base plate 104 having one side or both sides thereof attached to the piezoelectric base plate 102. In the disclosed structure shown in FIG. 6, the piezoelectric base plate 102 is attached to the bottom side of the elastic base plate 104. The driving shaft 108 has its axial one end rigidly fixed to the deformable thin plate 106. In the disclosed structure shown in FIG. 6, the driving shaft has its axial bottom end rigidly fixed to the upper lateral side portion of an elastic base plate 104 forming the deformable thin plate 106.
The piezoelectric base plate 102 has its thickness that may expand or contract itself and also has its surface that may contract or expand itself, when the voltage is applied across the piezoelectric base plate 102. The elastic base plate 104 will not undergo such deformations, however. When the voltage is then applied across the piezoelectric base plate 102, the deformable thin plate 106 will be bent upwardly or downwardly just like the bimetal or will be restored to its original shape as shown in FIG. 6. The driving shaft 108, whose movement is operatively associated with the displacement that is caused by the deformable thin plate 106, will be vibrated upwardly and downwardly as shown in FIG. 6.
The elastic base plate 104 and the piezoelectric base plate 102 have the diameter of several mm or the square of several mm as they are viewed in plane from the axial direction of the driving shaft 108. The driving shaft 108 has the diameter of about one mm. The vibrations mentioned above have the amplitude of one μm to several μm and the frequency of several ten kHz.
Although it is not specifically described in Patent Document 1, it is the practice in the prior art that the axial end of the driving shaft 108 is rigidly fixed to the deformable thin plate 106 by means of any appropriate adhesive agent. In the prior art, it is the practice that the adhesive agent is applied between the surface of the deformable thin plate 106 on the side on which the driving shaft 108 is rigidly fixed to the deformable thin plate 106 and the driving shaft 108 as well as on the peripheral areas around them to ensure they can be fixed with stability.
Patent Document 1: Japanese patent No. 2007-516688 publication